The Philippines’ armed forces said Wednesday that it had cordoned off a suspected "new terrorist group” in the Muslim south involved in days-long clashes that reportedly left around 20 militants and three soldiers dead.

Spokesperson Brig. Gen. Restituto Padilla told GMA News that the nameless armed group had been behind violence that broke out Saturday when 40 gunmen attacked a military detachment in Butig town, Lanao del Sur province.

He had earlier said that the number of fatalities on the militant side – whose number rose to around 80 gunmen – “is subject to verification” and that their motive remained unknown.

On Wednesday, Padilla cited a military source in saying that the armed group’s members were followers of a chief of a command of the country’s one-time largest Moro rebel group that is engaged in an ongoing peace process with the government.

Padilla, however, underlined that security forces and the MILF are coordinating through peace mechanisms under an ad hoc committee aimed at maintaining their cease-fire and combatting criminal syndicates and terrorist groups operating in the southern Muslim region of Mindanao island.

Several armed Muslim groups and a communist insurgency operate in conflict-ridden Mindanao.

The fighting comes at a time when the military has been conducting weeks of operations against a breakaway Muslim rebel group, the Bangsamoro Islamic Freedom Fighters (BIFF), in neighboring Maguindanao province.

Col. Noel J. Detoyato, Armed Forces public affairs office chief, said in a press briefing Tuesday that more than 30 BIFF members had died in less than three weeks of clashes after the group attacked a dredging project in Datu Salibo town.

The BIFF is opposed to the peace process between the government and the MILF – which it broke away from in 2008 – and has claimed allegiance to ISIL.

The law that seals the peace process – aimed at bringing an end to a separatist conflict that has killed around 150,000 people – is presently stalled in Congress, as the legislature has adjourned for election campaigning.